x86: x86 ptrace merge syscall trace

This moves the 64-bit syscall tracing functions into ptrace.c,
so that ptrace_64.c becomes entirely obsolete.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>